Differential gearing



F. E. CRAWFORD. DIFFERENTIAL GEARING. APPLICATION FILED APR-30, 1920.

Patented Jan. 31, 1922.

'3 SHEETS-$HEET l- INVENTOR mzafarfl,

WITNESSES F. E. CRAWFORD.

DIFFERENTIAL GEARING.

APPLICATION men APR. 30. I920.

1,404,836, Patented Jan. 31,1922.

3 SHEETS-SHEET 2- l/VVEIVTOR JET 0i awfor 1%? A TTOHNEYS F. E. CRAWFORD.

DIFFERENTIALGEARING.

. APPLICATION FILED APR. 30. 1920.

1,464,836. Patented Jan. 31,1922.

3 SHEETS-SHEET 3- INVENTOI? Zlfmzafmd;

liww i ATTORNEYS than is. rare T E N F i c i;

FRANK n. ofeawnoan, or ror'rna, NEBRASKA, assienon orironrr-nrnn PERonnr.

T0 HARRY novn onawronn Ann oscen. nnwre rain-Lona, onner RAVENNA,

nnnnesxai incense.

DIFFERENTIAL GEABING.

Specification of Letters Patent;

v Patented J an. 311, 1922.

Application filed has so, 1920. Serial in. 377,880.

ToaZZ whom it may concern:

Be it known that I, F RANK E. (lnAwronn, a citizen of the United States,and a'resident of Potter, in the county of Cheyenne and StateofNebraska, have invented cer tain new and useful; Improvements inDifferential Gearing, of which the, following is a specification. y

In differential gearing heretofore pro.- posed, completedifferentiationis secured or entirely prevented, there being no means to' restrictdifferentiation soas to prevent. one driving wheel exceeding inspeed ofrotation that of the engine andthus transferring all of the drivingpower to the outer driving wheel. With the ordinary difierentialgearing, such a condition exists when" an automobile is turning a cornerso that the outer driving wheel merely idles whilethe inner wheelreceives all of the power of the engine. This obviously places theentire driving strain on the inner wheel and as a result causesexcessive and uneven wearing of th moving parts in addition to a loss ofpower as a result of this distribution- It is the purpose of myinvention to provide a differential gearingv which automaticallylimitsits scope of diiierentiation, neither preventing or allowing ofcomplete differentiation so that power is suppliedto, both wheels at alltimes. The greatest I amount'of diiferentiation necessary under anyconditions is that whichallows of the carturning in the smallest circleofwhich its steering apparatus permits If while turning that smallestcircle the inner wheel makes three revolutions and the outer wheel fiverevolutions, then the ratio o'f3 :5 is the greatest difierentiationrequired inthat car. My invention allows of this maximumdifferentiationand yet prohibits any greater differentiation, while atthe same time permitting either wheel to act anywhere be tween the ratioof 3 :5 whilethe other wheel is compensating from 5 :3. .{Itwill thus beseen that differentiation is permitted and yet limited so that power isat all times applied to both wheels. i

, I will describe one form of differential gearing embodying myinvention and will then point out the novel features thereof in claims.

In the accompanying drawings:

Figure 1 is a view showing in vertical section one form of differentialgearing emhodyingmy invention.

Figure 2 is .a transverse sectional view takenon the line 2-2 of Figure1.

Figure 3 is a view showinglin top plan the gearing housing and the shaftcasing.

Flgure' i'is a detail View of certain of the gears and pinions shown inFigure 1. Figure 5 is a fragmentary detail perspect ve view of one ofthe brake shoes shown in Figure 2;

Figurelfi is a detailed perspective view ofone of thelevers showninFigure 2.

Figure 7 is a view showing in side elevat1on on of the actuating ringsfor the levers of the, brake shoes.

. Figure Sis a vertical sectionalview taken onthe line 88 of Figure 1and looking in the direction of the arrows. 1

Similar reference characters refer to similar parts in each of theseveral views particularly to Figure l, S and S" desigof. an automobile,such axle being enclosed ina sectional casing K which includes adifferential housing Ho The confronting ends of the sections S and, Sfare spaced apart and are provided with bevel gears and B respectivelywhich "constantly mesh with beveled planetary pinions P and P5interposed between the two and formed with stub shafts and whicharejournaled' in semi-spherical gears G and G, re spectively. As clearlyshown, in Figure 1 the semi-spherical gears G and G are arranged inreverse relation to each other with their confronting edges formed withteeth. These'gears G and Gt are rotatahly mounted upon the stub shaftsand p, the p 0 i Referring specifically to the drawings and P or P isclearly shown, this view being a detail of the two gears. The carrierband C has fixed thereto a ring gear R which is beveled and constantlymeshes with a driving gear D fixed to the rear end of the driving'shaftfAi that projects into the differential housing K in a mannerwhich will be clearly understoodQ At point where the shaft sections Sand S enterthe difi'erential housing H, the latter is formed withthickened portions 15 and 15 upon the confronting faces of which areformed annular bosses .16 and 16 The bosses 16 and 1e are partiallyembraced by beveled gears Eand E, respectively, which constantly meshwith i the semi-spherical gears G and G, Thegears E and E haveintegrally formed therewith drums M and M which are associated with thethickened portions 15 and l5. so as to provide compartments for thereception of brake shoes Fand F. As shown in Figure 2, the brake shoes F01"- one drum M or M are arranged in pairs with the shoes of each pairsupported for rocking movement upon the opposite ends of levers J or J.The levers J or J are-arranged at diametrically oppositepoints withrespect to the'corresponding boss 16 or 16* and are rockinglymounted'thereon by means of heads 17 'which fit in suitable socketsformed in the boss. The opposite ends of each lever J or J are providedwith heads 18 which fit in suitable sockets formed in the brake shoes Fand F as clearly shown in Figure 2 and so that when thelever is rockedabout the head 17, as a center the corresponding brake shoes will bemovedinto or out of engagement with the inner periphery of the drumaccording as the lever is rocked in one direction or the other. The twolevers J and J are biased to the positions shown in Figure'2 wherein allof the brake shoes are out of contact with the drum'M, by means ofcoiled contractile springs 19 which are connected to thelevers in themanner shown in Figure 2'. This biased position of the levers J and J .1term the intermediate position, and the positions which theymay occupywhen rocked in one direction or the other,

the two extreme positions. The levers are adapted to be'simultaneouslyactuated so as to occupy the intermediate position or either ofthe twoextreme positions by a ring, 20,

which, as illustrated to advantage in Figure 7, is provided atdiametrically opposite pointswith pins 21 that are adapted to work iwithin recesses 22 formed inthe levers J and J, as clearly showninFigures 2 and 6. The ring 20 in its applied position is disposedwithin a circular recess 23 formed in the thickened portion 15 or 15 ofthe'housing H, as clearly shown in Figure 8. The ring is adapted to berotated in one direction or the other by a'rod 24 which extendstangentially from the ring and exteriorly of the differenrotation of thetial housing where it is connected to the gear shifting lever of anautomobile so that it can be actuated simultaneously with the operationof the gear shifting lever. Upon rotation of the ring 20, the pins 21engage the walls of the recesses 22 thus'causing the rocking of thelevers J and J about the heads 17 as centers so that they are caused toaccupy one extreme position or the other depending upon which directionthering 20 is rotated. V V

From the manner in which the brake shoes F are mounted upon, the leversJ and J, it will be evident that in" one extreme position of the leversone brakes'hoe of each pair will contact the drum M, whilein the other.ex-

treme' position "of the levers, these brake shoes will be moved out ofengagement with the brake drum and the remaining shoes moved intoengagement with the drum. In the intermediate position] of the leversneither pair of shoes contacts with the drum so that the latter is freeto rotate; Because of the fact that the several brakeshoes are mountedfor rocking movement? upon the levers, such shoes are capable ofindependent rockingmovement so as to be moved to'such a position thatthey will be ineffective to brake the movement of the drum when thelatter'is rotated in "a predetermined direc tion. This operation will bemore clearly understood from a consideration of the op eration of theentire gearing. V V s v The operation of the gearing isas follows: Withthe driving shaft A rotating, driving gear D efi'ects rotation of thecarrier band Cthrough the ring gear R so that rotation of the planetarypinions P and P with the semi-spherical gears G and G" is secured, aboutthe driving axle as a center. Upon pinions'P and P, gears'B and B eflectrotation of the shaft sections S and S so that the driving wheels (notshown) of the vehicle which are secured to the shaft sections, aredriven. During this movement, the gears G and G" rotate the gears E andE which rotation of the drums M and M in the same direction. r

Now let it be assumed that a vehicle equipped with this differentialgearing is travelling forward and the 'levers J and J occupy one extremeposition wherein the brake shoes F and F allow of the free rotation ofthe drums in the direction of rotation of the shaft sections S and S butlook" the drums against rotation in the opposite direction. When bothwheels engage the ground with equal traction so that equal resistance isoffered to the shaft sections, equal power will be applied to the shaftsections in the usual manner. However, when one of the wheels, say forexamplethe wheel on the shaft section S, loses its traction as latter inturn eflect semi-spherical gears G and G will tend to rotate about thestub shafts pand p causing a retardation of the drum M. Should its lossof traction causeit to make five revolutions while the other makesthree, then the drum l has ceased rotating. Should its tendency be toincrease this ratio then the tendency of the drum M would be to rotaterearwardly which it cannot do on account of the brake shoes which areconstantly guarding against a backward motion. With the drum lockedagainst rotation rearwardly, it is obvious that the gears E become thefulcrum point, the axes of the gears G and Gr the power, and the gear Bthe resistance. Since the motion of the gears G and G on their own axesis limited,

naturally the differentiation is also limited, but the differential isnot lockedas it will continue to operate under these conditions in thefollowing manner: With the gear E of a diameter equal to one half of thediameter of the gears G and G, the wheel on the shaft. S will make threerevolutions while the ring gear R is making four revolutions, the wheelof the shaft S five revolutions, and the drum M eight revolutions. Ifloss of traction occurs of the wheel on the shaft S, then the drum M islooked against backward rotation thus forcing the left wheel toturnahead three revolutions while the ring gear R makes four revolutions,the right wheel five revolutions and the drum M eight revolutions.

From this operation it will be seen that irrespective of the differencein resistance offered by the two driving wheels, power is applied toboth of the shaft sections so that at no time is the differentiatingaction complete as in the usual form of differential gearing.

The differential gearing will operate in a reverse manner to that justdescribed when the vehicle is in reverse mot-ion. All that is necessaryis to shift the levers J and J to their other extreme position bymanipulation of the ring 20 through the medium of the rod 23 so that thebrake shoes will lock the drums against forward movement to permitunrestricted movement of the same rearwardly.

Although I have herein shown and described only one form of differentialgearing embodying my invention, it is to be understood that variouschanges and modifications may be made herein without departing from thespirit of the invention and the splrit and scope of the appended claims.

What I claim is:

l. A differential gearing comprising, shaft sections, gears fixed to thesections, planetary pinions meshing with said gears, a carrier bandrotatably supporting said pinions semi-spherical gears rotatable on saidband, bevel gears rotatable on said sections and meshing with saidsemi-spherical gears, a ring gear fixed to said band, a driving gearmeshing with said ring gear, drums carried by the bevel gears, a housingencasing all of said gears, levers fulcrumed onsaid housing, shoespivoted on said levers, and manually operable means for rocking saidlevers to cause said shoes to occupy an intermediate position whereinthey disengage said drums and two extreme positions wherein they locksaid drums against rotation in either direction.

2. A differential gearing comprising, shaft sections, gears fixed to thesections, planetary pinions meshing with said gears, a carrier bandrotatably supporting said pinions, semi-spherical gears rotatable onsaid band, bevel gears rotatable on said sections and meshing with saidsemi-spherical gears, a ring gear fixed to said band, a driving gearmeshing with said ring gear, drums carried by the bevel gears, a housingencasing all of said gears, levers fulcrumed on said'housing, shoespivoted on said levers, and rings rotatably mounted in said housing andengageable with said levers to rock the same when the ring is rotated ineither direction, whereby said shoes are caused to engage said drums tolock the latter against movement in one direction.-

FRANK E. CRAWFORD.

